Abstract: A vehicle brake system and a method of control. A friction brake torque and a secondary brake torque may be applied with a friction and secondary brakes, respectively, under various operating conditions, such as when a brake torque command is less than a threshold brake torque command.

Abstract: A brake system and a method of controlling a brake system. The method may include indirectly estimating an air gap between a brake friction member and a brake pad assembly based on a position signal from a position sensor that detects cycling of the friction brake and a further signal indicative of an amount of brake force used to engage the brake pad assembly with the brake friction member. The air gap may be adjusted when an estimated air gap differs from a desired air gap.

Abstract: A brake system and a method of control. An air gap between a brake friction member and a brake pad assembly may be indirectly estimated. The air gap may be adjusted when the estimated air gap exceeds a desired air gap.

Abstract: A vehicle brake system and a method of control. The vehicle brake system may include a friction brake and a secondary brake that may be applied to slow rotation of a vehicle wheel when a wheel slip condition is detected.

Abstract: A brake system and a method of control. An air gap between a brake friction member and a brake pad assembly may be indirectly estimated. The air gap may be adjusted when the estimated air gap exceeds a desired air gap.

Abstract: A vehicle brake system and a method of control. The vehicle brake system may include a friction brake and a secondary brake that may be applied to slow rotation of a vehicle wheel when a wheel slip condition is detected.

Abstract: A vehicle brake system and a method of control. A friction brake torque and a secondary brake torque may be applied with a friction and secondary brakes, respectively, under various operating conditions, such as when a brake torque command is less than a threshold brake torque command.

Abstract: A control system and method for a steer-by-wire system with the passive resistance torque is provided. The control system includes a controller configured to compensate for a passive resistance torque and to generate the required active torque using a three loop control structure: torque feedback loop, rate feedback loop, and steering wheel angle feedback loop. The torque feedback loop is based on an estimated steering torque signal calculated from a steering angle signal, a steering angle rate signal, and a motor current signal.

Abstract: A bi-directional smooth transition switch with bumpless transfer is disclosed. It is composed of two feedback loops, each with feedback and forward-loop compensators. During loop operation, one feedback loop is active, while the other is inactive. The smooth transition switch operates in the following manner. The switch output is measured. Next, an error signal is formed as the difference between the forward-loop compensator output and the switch output, which is fed to the input of a high gain feedback compensator. The output of the feedback compensator is a feedback signal. When no switching occurs, the feedback signal remains zero in the active loop, and the output signal of the inactive loop will track the output signal of the active loop. When the switchover occurs, the inactive loop will replace the original active loop and provide smooth transition switch's output.

Abstract: A control system and method for a steer-by-wire system with the passive resistance torque is provided. The control system includes a controller configured to compensate for a passive resistance torque and to generate the required active torque using a three loop control structure: torque feedback loop, rate feedback loop, and steering wheel angle feedback loop. The torque feedback loop is based on an estimated steering torque signal calculated from a steering angle signal, a steering angle rate signal, and a motor current signal.

Abstract: A method and system for sensing angular displacement is provided. More specifically, the system includes a brushless DC motor, three Hall effect sensors, an angular displacement signal processor, and an output state observer. The Hall effect sensors provide three electrical angles of the motor rotor which are used in an angular displacement signal processor that is implemented in hardware and software. The angular displacement signal processor provides an improved resolution angular displacement output. Based on the angular displacement output from angular displacement signal processor and the motor control command signal from the motor drive, an output state observer is applied to generate a high resolution angular displacement signal.

Abstract: The present invention involves a method and system of initial aligning wheels of vehicle steer-by-wire systems with two independent front road wheels in the real time. The method comprises providing a steering wheel control sub-system and a road wheel control sub-system, providing an initial alignment unit and procedure to align the road wheels and steering wheel, and receiving relative and absolute steering wheel angles and road wheel angles. The method further includes generating wheel aligning reference angles based on the relative and absolute wheel angle, generating the switch control signal based wheel aligning reference angles using the logic operation with the threshold, and determining the steer-by-wire systems in the control state or in the initial alignment state.

Abstract: The present invention provides systems and methods of friction compensation in a steer-by-wire system or in a general electric steering system using control, estimation and modeling methodologies. A friction compensator in the steer-by-wire control system produces a friction compensating torque value equal and opposite in sign to the instantaneous friction torque. This compensating friction torque is added to the steering system control signal to eliminate the effects of friction present in the system such that the system performances are improved. The friction compensator produces the compensating friction torque according to one of two schemes: model-based or non-model based. The model-based scheme encompasses a number of different methods including a standard model-based scheme, a disturbance torque observer-based scheme, an adaptive friction compensation scheme, or a model reference adaptive control scheme. The non-model based scheme includes a fuzzy logic scheme.

Abstract: The present invention involves a system and method of model-based fault detection for a vehicle steer-by-wire system. The method includes providing a steer-by-wire fault detection unit to implement fault detection for the fault occurrence in sensors, actuators, and the controlled plant. The steer-by-wire fault detection unit is composed of a residual generator and decision-making unit. The residual generator generates a series of residual signal which are difference between the estimation signals based on a steer-by-wire controlled plant mathematical model and the actual measurement signals of steer-by-wire controlled plant. The decision making unit determines whether any faults have occurred by applying a fault test rule for residual signals.

Abstract: The present invention involves a method for initial synchronization of steering wheel and a road wheels in a steer-by-wire system of a vehicle when the system is first powered. The method includes providing a steering wheel control system and a road wheel control system. The method further includes sensing relative angles and the absolute angles of the steering wheel, road wheel, and right road wheel. The method further includes generating an augmented steering wheel angle, an augmented left road wheel angle, and an augmented right road wheel angle based on the relative angle and initial value of the absolute angles of the steering wheel and road wheels. The method further includes using the augmented steering wheel angle as a feedback signal to the steering wheel control system and the augmented left and right road wheel angles feedback signals to the road wheels control system.

Abstract: The present invention involves a system and method of model-based fault detection for a vehicle steer-by-wire system. The method includes providing a steer-by-wire fault detection unit to implement fault detection for the fault occurrence in sensors, actuators, and the controlled plant. The steer-by-wire fault detection unit is composed of a residual generator and decision-making unit. The residual generator generates a series of residual signal which are difference between the estimation signals based on a steer-by-wire controlled plant mathematical model and the actual measurement signals of steer-by-wire controlled plant. The decision making unit determines whether any faults have occurred by applying a fault test rule for residual signals.

Abstract: A method and system for sensing angular displacement is provided. More specifically, the system includes a brushless DC motor, three Hall effect sensors, an angular displacement signal processor, and an output state observer. The Hall effect sensors provide three electrical angles of the motor rotor which are used in an angular displacement signal processor that is implemented in hardware and software. The angular displacement signal processor provides an improved resolution angular displacement output. Based on the angular displacement output from angular displacement signal processor and the motor control command signal from the motor drive, an output state observer is applied to generate a high resolution angular displacement signal.

Abstract: The present invention involves a method for initial synchronization of steering wheel and a road wheels in a steer-by-wire system of a vehicle when the system is first powered. The method includes providing a steering wheel control system and a road wheel control system. The method further includes sensing relative angles and the absolute angles of the steering wheel, road wheel, and right road wheel. The method further includes generating an augmented steering wheel angle, an augmented left road wheel angle, and an augmented right road wheel angle based on the relative angle and initial value of the absolute angles of the steering wheel and road wheels. The method further includes using the augmented steering wheel angle as a feedback signal to the steering wheel control system and the augmented left and right road wheel angles feedback signals to the road wheels control system.

Abstract: The present invention involves a system and method of controlling a variable steering ratio of a vehicle steer-by-wire system. The variable steering ratio control varies the steering ratio continuously according to steering angle and vehicle speed. The method comprises sensing an actual steering wheel angle and an actual speed of the vehicle and converting the actual steering wheel angle and vehicle speed into values in fuzzy sets based on a steering wheel angle and vehicle speed membership functions with linguistic term labels. The method further includes determining a corresponding degree of membership of the steering wheel angle and vehicle speed. The method further includes inferring a fuzzy road wheel reference angle output value by determining the degree of membership function for the road wheel reference angle using fuzzy rules based on the degrees of steering angle and the vehicle speed. The method further includes converting a fuzzy road wheel angle into an actual road wheel angle.

Abstract: The present invention involves a method of controlling a vehicle steer-by-wire system having two independent road wheels. In one embodiment, the method comprises providing a steering wheel control sub-system to generate road wheel reference angles and to produce steering feel for a vehicle driver. The method further includes providing a road wheel control subsystem with servo control structure having road wheel angles and angular rates feedbacks including a road wheel controlled plant and a road wheel controller for controlling actual road wheel angles to track to road wheel reference angles. Moreover, a robust control is implemented in the road wheel controller to overcome affects of uncertainties and disturbances from the steer-by-wire system, vehicle, and external environment.